Common Registration Assessment, Part 1

Pseudoephedrine tablet and liquid doses in 24 hours for the GPhC assessment

Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.

Published 30 October 2026. Independent revision material, not GPhC questions, not for patient care.

Woman lying in bed using a tissue with cold symptoms
Photo from Pexels, used under the Pexels licence. It is a stock image and does not show the exercise.

The NHS states that adults and children aged 12 years and over taking pseudoephedrine tablets swallow 1 tablet up to 4 times a day, wait at least 4 hours between each dose, and do not take more than 4 tablets in 24 hours.

The NHS states that pseudoephedrine liquid contains 30mg of pseudoephedrine in 5ml, that adults and children aged 12 years and over take two 5ml doses (60mg), and that children aged 6 to 11 years take one 5ml dose (30mg), up to 4 times a day and no more than 4 doses in 24 hours.

The NHS advises that adults should only take pseudoephedrine for short-term relief of symptoms.

Each question fixes the values needed for its arithmetic. Write the unit beside every step and distinguish a single dose from a daily total or course supply. All prescriptions and patients here are fictional; these are revision materials, not for patient care.

The method

  1. Identify whether the question uses tablets or liquid, and the age band stated.
  2. Apply the stated concentration (30mg in 5ml) before any dose conversion.
  3. Calculate one dose first, then scale by the stated frequency, keeping within the 4 doses in 24 hours limit.
  4. Convert ml to mg or mg to ml using the stated 30mg per 5ml ratio.
  5. Keep tablet counts and liquid volumes as separate units throughout.

Three practice questions

Work each one on paper first, then open the answer. All patients and prescriptions are fictional.

Question 1

A fictional adult takes 1 pseudoephedrine tablet at the maximum stated frequency. How many tablets is that in 24 hours, and over 3 days at the same maximum?

Show the answer

Answer: 4 tablets in 24 hours; 12 tablets over 3 days

Working: Maximum 4 tablets in 24 hours; 4 tablets x 3 days = 12 tablets.

Question 2

A fictional adult takes the stated liquid dose of 60mg. The liquid contains 30mg in 5ml. How many ml is one dose?

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Answer: 10ml

Working: 60mg / 30mg = 2; 2 x 5ml = 10ml (two 5ml doses).

Question 3

A fictional child aged 6 to 11 takes one 5ml dose (30mg) 4 times in a day. How many mg and how many ml is that in total?

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Answer: 120mg in 20ml

Working: 30mg x 4 doses = 120mg; 5ml x 4 doses = 20ml.

NHS: Pseudoephedrine

https://www.nhs.uk/medicines/pseudoephedrine/

Where marks are lost

  • Exceeding the stated maximum of 4 tablets or 4 doses in 24 hours.
  • Using the adult liquid dose for a child aged 6 to 11.
  • Treating arithmetic as evidence that a real supply is clinically suitable.

Frequently asked questions

Are these official assessment questions?

No. They are original revision exercises, not official GPhC questions and not for patient care.

Can a 24-hour total justify a longer course?

No. Follow the frequency and duration in the exercise. Pseudoephedrine is for short-term relief; real use beyond that needs professional advice.

How should I check the answer?

Check the requested unit, then work backwards from the quantity to the stated dose and duration.

Sources

The questions above are original and use fictional patients and prescriptions. PreRegExamPrep is not affiliated with or endorsed by the General Pharmaceutical Council.

Practise until the method is automatic

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More calculation topics

See also the formula sheet, the eight sample questions and the approved calculator page.